Final answer:
The denial termed 'Claim covered by other insurer' occurs when a health insurance company recognizes another insurance provider should be responsible for a liability case.
Step-by-step explanation:
When a liability case is submitted to health insurance and the claim is denied because it is covered by another insurer, the correct term for this type of denial is d. Claim covered by other insurer. In such scenarios, the health insurance company identifies that there is another insurance policy in play that should be responsible for the claim, often due to coordination of benefits. This arises in situations where multiple insurance policies could potentially cover the same claim, and the primary policy must take precedence.